commctrl: initial button theming support

[Jonathan Wilson]

Frank Richter wrote:

> Frank Richter <frank.richter at gmail.com>
> Add theming support. When comctl32.dll is attached to a thread, a CBT
> hook is set up for the current thread which intercepts all window
> creations. There, the class name of the window is checked. In case of a
> known class, the window is subclassed, and the subclass is handling the
> theming-related stuff.
> Add initial theming support for the "Button" class.
Not that I am any kind of expert here but would it not make sense to 
implement things the way windows does it? From what I know, windows 
implements it via activation contexts and manifests.